Oxygen scavenging high barrier polyamide compositions for packaging applications

ABSTRACT

Oxygen barrier polyamide compositions exhibiting high oxygen scavenging capability suitable for extended shelf-life, packaging applications. Thus a polyamide composition comprises a polyamide homopolymer, copolymer, or blends thereof, and at least one polyamide reactive, oxidizable polydiene or oxidizable polyether. The polyamide products are particularly suited to making barrier packaging articles such as monolayer or multi-layer films, sheets, thermoformed containers and coinjection/coextrusion blow molded bottles comprising PET, polyolefin or polycarbonate as structural layers. Such articles are useful in a variety of oxygen-sensitive food, beverage, pharmaceutical and health care product packaging applications.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to oxygen barrier polyamide compositionsexhibiting high oxygen scavenging capability suitable for extendedshelf-life packaging applications. The polyamide products areparticularly suited for producing barrier packaging articles such asmonolayer or multi-layer films, sheets, thermoformed containers andcoinjection/coextrusion blow molded bottles comprising polyethyleneterephthalate (PET), polyolefin or polycarbonate as structural layers.Such articles are useful in a variety of oxygen-sensitive food,beverage, pharmaceutical, and health care product packagingapplications.

2. Description of the Related Art

It is well known in the art to provide polyamide based packagingarticles such as films, bottles and containers, which are useful forfood packaging. Many such articles are made of multiple layers ofdifferent plastics in order to achieve the desired barrier properties.For example, U.S. Pat. Nos. 5,055,355 and 5,547,765 teach laminates ofpolyamides and ethylene vinyl alcohol, copolymers which have good oxygenbarrier properties.

In order to enhance freshness preservation, it is standard practice topackage food and other materials within laminated packaging materialthat generally includes a barrier layer, that is, a layer having a lowpermeability to oxygen.

The sheet material can be thin, in which event it is wrapped around thematerial being packaged, or it can be sufficiently thick that it forms ashaped container body. It is known to include an oxygen scavenger insheet material. The oxygen scavenger reacts with oxygen that is trappedin the package or that permeates into the package. This is described,for instance, in U.S. Pat. Nos. 4,536,409 and 4,702,966. U.S. Pat. No.4,536,409, for example, describes cylindrical containers formed fromsuch sheet material.

Various types of oxygen scavengers have been proposed for this purpose.U.S. Pat. No. 4,536,409 recommends potassium sulfite as an oxygenscavenger. U.S. Pat. No. 5,211,875 discloses, the use of unsaturatedhydrocarbons as oxygen scavengers in packaging films. It is known in theart that ascorbic acid derivatives as well as sulfites, bisulfites,phenolics, etc. can be oxidized by molecular oxygen, and can thus serveas an oxygen scavenging material. U.S. Pat. No. 5,075,362 discloses theuse of ascorbate compounds in containers as oxygen scavengers. U.S. Pat.Nos. 5,202,052 and 5,364,555 describe polymeric material carrierscontaining oxygen scavenging material. These polymeric carriers for theoxygen scavenging material include polyolefin, PVC, polyurethanes, EVAand PET. U.S. Pat. Nos. 5,021,515, 5,049,624 and 5,639,815 disclosepackaging materials and processes therefor which utilize a polymercomposition which is capable of scavenging oxygen; such compositionsinclude an oxidizable organic polymer component, preferably a polyamide(preferably MXD6) and a metal oxidation promoter (such as a cobaltcompound). These compositions can be used with PET, for example.

U.S. Pat. No. 5,529,833 describes the use a composition comprising anethylenically unsaturated hydrocarbon oxygen scavenger which isincorporated into a film layer and used for making packaging for oxygensensitive products. The oxygen scavenger is catalyzed by a transitionmetal catalyst and a chloride, acetate, stearate, palmitate,2-ethylhexanoate, neodecanoate or naphthenate counterion. Preferredmetal salts are selected from cobalt (II) 2-ethylhexanoate and cobalt(II) neodecanoate. Because water deactivates the oxygen scavengercomposition, the composition can only be used for packaging for drymaterials.

There remains a need for the selection of a substrate which can provideoxygen scavenging in order to reduce the oxidation of the constituentscontained therein. Accordingly, it is an object of the invention toprovide an improved oxygen scavenging blend for use in coatingsubstrates for food packaging applications.

The present invention provides a single polyamide layer which is aneffective oxygen barrier as well as a multiple layered structure formedfrom the polyamide layer to provide even more effective oxygen barrierproperties. These high oxygen barrier polyamide compositions exhibitunusually high oxygen scavenging capability suitable for extendedshelf-life, packaging applications. The oxygen scavenging polyamidecompositions may be prepared by a reactive extrusion process ofcompounding polyamides with a small amount of a low molecular weight,oxidizable polydiene or polyether polymer. The polyamide products areparticularly suited to making barrier packaging articles which areuseful in a variety of oxygen-sensitive applications.

SUMMARY OF THE INVENTION

The invention provides a polyamide composition which comprises apolyamide homopolymer, copolymer, or blends thereof, and at least onepolyamide reactive, oxidizable polydiene or oxidizable polyether.

The invention also provides a polyamide composition which comprises ablend of a polyamide homopolymer, copolymer, or blends thereof, and atleast one polyamide reactive, oxidizable polydiene or oxidizablepolyether.

The invention further provides a polyamide composition which comprisesthe reaction product of a polyamide homopolymer, copolymer, or blendsthereof, and at least one polyamide reactive, oxidizable polydiene oroxidizable polyether.

The invention still further provides a oxygen barrier film comprising alayer of a polyamide composition which comprises a polyamidehomopolymer, copolymer, or blends thereof, and at least one polyamidereactive, oxidizable polydiene or oxidizable polyether.

The invention yet further provides a multilayer article which comprisesan oxygen barrier polyamide composition layer comprising a polyamidehomopolymer, copolymer, or blends thereof, and at least one polyamidereactive, oxidizable polydiene or oxidizable polyether; and athermoplastic polymer layer on one or both sides of the polyamidecomposition layer.

The invention also provides a shaped article which comprises a polyamidecomposition which comprises a polyamide homopolymer, copolymer, orblends thereof, and at least one polyamide reactive, oxidizablepolydiene or oxidizable polyether.

The invention further provides a process for producing a polyamidecomposition which comprises melting a polyamide homopolymer, copolymer,or blends thereof, and blending the molten polyamide homopolymer,copolymer, or blend thereof with at least one polyamide reactive,oxidizable polydiene or oxidizable polyether to form a mixture, and thencooling the mixture.

The invention also provides a process for producing an oxygen barrierpolyamide film which comprises melting a polyamide homopolymer,copolymer, or blends thereof, and blending the molten polyamidehomopolymer, copolymer, or blend thereof with at least one polyamidereactive, oxidizable polydiene or oxidizable polyether to form amixture, and then extruding, casting or blowing the mixture into a filmwith subsequent cooling.

The invention also provides a process for producing an oxygen barrierpolyamide film which comprises melting a composition comprising apolyamide homopolymer, copolymer, or blends thereof, and at least onepolyamide reactive, oxidizable polydiene or oxidizable polyether, andthen extruding, casting or blowing the composition into a film withsubsequent cooling.

The invention also provides a process for producing a multilayer articlewhich comprises melting a polyamide homopolymer, copolymer, or blendsthereof, and blending the molten polyamide homopolymer, copolymer, orblend thereof at least one polyamide reactive, oxidizable polydiene oroxidizable polyether to form a mixture; separately melting athermoplastic polymer composition; and then coextruding, casting,blowing, thermoforming, blow molding or coinjecting the mixture andthermoplastic polymer composition into a multilayer article, withsubsequent cooling.

The invention also provides a process for producing a multilayer articlewhich comprises melting a composition comprising a polyamidehomopolymer, copolymer, or blends thereof, and at least one polyamidereactive, oxidizable polydiene or oxidizable polyether; separatelymelting a thermoplastic polymer composition; and then coextruding,casting, blowing, thermoforming, blow molding or coinjecting the mixtureand thermoplastic polymer composition into a multilayer article, withsubsequent cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a graph of the oxygen transmission data for Examples 6 and9 and Comparative Example 1.

FIG. 2 shows a graph of the oxygen transmission data for Examples 11 and13 and Comparative Examples 1, 4 and 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the present invention, an improved polyamide composition is preparedby combining a polyamide homopolymer, copolymer, or blends thereof, andand oxidizable polydiene or polyether. Preferably the composition alsocomprises a metal carboxylate salt catalyst and a nanoscale clay.

The preferred polyamide homopolymer or copolymer is selected fromaliphatic polyamides and aliphatic/aromatic polyamides having amolecular weight of from about 10,000 to about 100,000. Generalprocedures useful for the preparation of polyamides are well known tothe art. Useful diacids for making polyamides include dicarboxylic acidswhich are represented by the general formula

HOOC—Z—COOH

wherein Z is representative of a divalent aliphatic radical containingat least 2 carbon atoms, such as adipic acid, sebacic acid,octadecanedioic acid, pimelic acid, suberic acid, azelaic acid,dodecanedioic acid, and glutaric acid. The dicarboxylic acids may bealiphatic acids, or aromatic acids such as isophthalic acid andterephthalic acid. Suitable diamines for making polyamides include thosehaving the formula

 H₂N(CH₂)_(n)NH₂

wherein n has an integer value of 1-16, and includes such compounds astrimethylenediamine, tetramethylenediamine, pentamethylenediamine,hexamethylenediamine, octamethylenediamine, decamethylenediamine,dodecamethylenediamine, hexadecamethylenediamine, aromatic diamines suchas p-phenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylsulphone, 4,4′-diaminodiphenylmethane, alkylated diamines such as2,2-dimethylpentamethylenediamine, 2,2,4-trimethylhexamethylenediamine,and 2,4,4 trimethylpentamethylenediamine, as well as cycloaliphaticdiamines, such as diaminodicyclohexylmethane, and other compounds. Otheruseful diamines include heptamethylenediamine, nonamethylenediamine, andthe like.

Useful aliphatic polyamide homopolymers include poly(4-aminobutyricacid) (nylon 4), poly(6-aminohexanoic acid) (nylon 6, also known aspoly(caprolactam)), poly(7-aminoheptanoic acid) (nylon 7),poly(8-aminooctanoic acid)(nylon 8), poly(9-aminononanoic acid) (nylon9), poly(10-aminodecanoic acid) (nylon 10), poly(11-aminoundecanoicacid) (nylon 11), poly(12-aminododecanoic acid) (nylon 12),poly(hexamethylene adipamide) (nylon 6,6), poly(hexamethylenesebacamide) (nylon 6,10), poly(heptamethylene pimelamide) (nylon 7,7),poly(octamethylene suberamide) (nylon 8,8), poly(hexamethyleneazelamide) (nylon 6,9), poly(nonamethylene azelamide) (nylon 9,9),poly(decamethylene azelamide) (nylon 10,9), poly(tetramethyleneadipamide (nylon 4,6), caprolactam/hexamethylene adipamide copolymer(nylon 6,6/6), hexamethylene adipamide/caprolactam copolymer (nylon6/6,6), trimethylene adipamide/hexamethylene azelaiamide copolymer(nylon trimethyl 6,2/6,2), hexamethyleneadipamide-hexamethylene-azelaiamide caprolactam copolymer (nylon6,6/6,9/6), poly(tetramethylenediamine-co-oxalic acid) (nylon 4,2), thepolyamide of n-dodecanedioic acid and hexamethylenediamine (nylon 6,12),the polyamide of dodecamethylenediamine and n-dodecanedioic acid (nylon12,12), as well as blends and copolymers thereof and other polyamideswhich are not particularly delineated here.

Of these polyamides, preferred polyamides include polycaprolactam, whichis also commonly referred to as nylon 6, and polyhexamethyleneadipamide, which is also commonly referred to as nylon 6,6, as well asmixtures of the same. Of these, polycaprolactam is most preferred.

Polyamides used in the practice of this invention may be obtained fromcommercial sources or prepared in accordance with known preparatorytechniques. For example, poly(caprolactam) can be obtained fromHoneywell International Inc., Morristown, N.J. under the trademarkCAPRON®. Suitable variants of CAPRON® for use as a first polyamide inthe present invention include CAPRON® 8200 nylon, a balanced nylon 6having a formic acid viscosity (FAV) of 75, CAPRON® 1767 nylon, abalanced nylon 6 having an FAV of 35, and CAPRON® 8224HSL nylon, a heatstabilized, lubricated nylon 6 having an FAV of 60. A suitable variantof CAPRON® nylon for use as a second polyamide includes CAPRON® 1250nylon, an amine-terminated nylon 6 with a FAV of 60 and having terminalamino groups of 70 to 78 milliequivalents per gram.

Exemplary of aliphatic/aromatic polyamides include poly (2,2,2-trimethylhexamethylene terephthalamide), poly(m-xylylene adipamide) (MXD6),poly(p-xylylene adipamide), poly(hexamethylene terephthalamide) (nylon6,T), poly(hexamethylene isophthalamide) (nylon 6, I),poly(dodecamethylene terephthalamide), polyamide 6T/6I,poly(tetramethylenediamine-co-isophthalic acid) (nylon 4,I), polyamide6/MXDT/I, polyamide MXDI, hexamethyleneadipamide/hexamethylene-isophthalamide (nylon 6,6/61), hexamethyleneadipamide/hexamethyleneterephthalamide (nylon 6,6/6I) and as well asothers which are not particularly delineated here. Blends of two or morealiphatic/aromatic polyamides and/or aliphatic polyamides can also beused. Aliphatic/aromatic polyamides can be prepared by known preparativetechniques or can be obtained from commercial sources. Other suitablepolyamides are described in U.S. Pat. Nos. 4,826,955 and 5,541,267,which are incorporated herein by reference.

The polyamide component is present in the overall composition in anamount of from about 80% to about 99.9% by weight, preferably from about90% to about 99% and more preferably from about 95% to about 98%.

The composition of the current invention also contains a functional,nylon reactive, oxidizable polydiene or polyether as an oxygenscavenger. Such are low molecular weight, small particles which arecompatible and uniformly dispersible in the polyamide. Preferably thenylon reactive, oxidizable polydiene or polyether comprises an epoxy oranhydride functionality such that it reacts with the carboxyl or aminoend groups of the polyamide. The functionality in the polydiene orpolyether may also react with amide group in the polyamide backbone. Thefunctionality can be pendant to the backbone or at the chain ends of thepolydiene or polyether. The preferred functional polydienes arefunctional polyalkadiene oligomers which can have the following generalbackbone structure:

where R₁, R₂, R₃ and R₄ can be the same or different and can be selectedfrom hydrogen (—H) or any of the lower alkyl groups (methyl, ethyl,propyl, butyl etc.). R₂ & R₃ may also be a chloro (—Cl) group.Illustrative of the backbone structure are polybutadiene (1,4 or 1,2 ormixtures of both), polyisoprene (1,4 or 3,4), poly 2,3-dimethylbutadiene, polychloroprene, poly 2,3-dichlorobutadiene, polyallene,poly1,6-hexatriene, etc.

Specific non-limiting examples of functional, oxidizable polydienes assuitable oxygen scavengers include epoxy functionalized polybutadiene(1,4 and/or 1,2), maleic anhydride grafted or copolymerizedpolybutadiene (1,4 and/or 1,2), epoxy functionalized polyisoprene, andmaleic anhydride grafted or copolymerized polyisoprene.

Specific non-limiting examples of functional oxidizable polyethers asoxygen scavengers include amine, epoxy or anhydride functionalizedpolypropylene oxide, polybutylene oxide (2,3 or 1,2) and polystyreneoxide. The preferred oxygen scavenger is an epoxy functionalpolybutadiene oligomer. The oxygen scavenger is present in the polyamidecomposition as a large number of small particles. The molecular weightof the functional polydiene or polyether oligomer may range from about500 about to 5,000, preferably from about 750 to about 3000 and mostpreferably from about 1000 to about 2000. It is present in the overallcomposition in an amount of from about 0.1% to about 10% by weight,preferably from about 1% to about 10% and more preferably from about 2%to about 5%. The functional, oxidizable polydiene or polyether is in theform of particles whose average particle size is in the range of fromabout 10 nm to about 1000 nm, wherein the particles are substantiallyuniformly distributed in the polyamide. The polyamide composition maycomprise either a blend of the polyamide and the polydiene or polyether,or a reaction product of the polyamide with the oxidizable polydiene orpolyether.

Preferably the composition further comprises a metal fatty acid saltcatalyst such as a low molecular weight metal carboxylate salt catalyst.Suitable metal fatty acid salt catalysts have a counterion which is anacetate, stearate, propionate, hexanoate, octanoate, benzoate,salicylate, and cinnamate or combination thereof. Preferably the metalfatty acid salt catalyst is a cobalt, copper or ruthenium, acetate,stearate, propionate, hexanoate, octanoate, benzoate, salicylate orcinnamate, or combinations thereof. The preferred metal carboxylate iscobalt, ruthenium or copper carboxylate. Of these the more preferred iscobalt or copper carboxylate and the most preferred is cobaltcarboxylate. It is present in the overall composition in an amount offrom about 0% to about 1% by weight, preferably from about 0.001% toabout 0.5% and more preferably from about 0.005% to about 0.1%. The mostpreferred range is from about 0.01% to about 0.05%.

Preferably the composition further comprises a nanometer scale dispersedclay. Suitable clays are described in U.S. Pat. No.5,747,560, which isincorporated herein by reference. Preferred clays non-exclusivelyinclude a natural or synthetic phyllosilicate such as montmorillonite,hectorite, vermiculite, beidilite, saponite, nontronite or syntheticflouromica, which has been cation exchanged with a suitableorganoammonium salt. The preferred clay is montmorillonite, hectorite orsynthetic flouromica. The more preferred clay is the montmorillonite orhectorite. The most preferred clay is montmorillonite. The preferredorganoammonium cation for treating the clay isN,N′,N″,N′″Bis(hydroxyethyl), methyl, octadecyl ammonium cation orω-carboxy alkylammonium cation, i.e., the ammonium cation derived suchω-aminoalkanoic acids as 6-aminocaproic acid, 11-aminoundecanoic acid,12-aminododecanoic acid. The preferred fine dispersions of nanometerscale silicate platelets are obtained either via an in-situpolymerization of polyamide forming monomer(s) or via melt compoundingof polyamide in the presence of the organoammonium salt treated clay.The clay has an average platelet thickness in the range of from about 1nm to about 100 nm and an average length and average width each in therange of from about 50 nm to about 500 nm. It is present in the overallcomposition in an amount of from about 0% to about 10% by weight,preferably from about 2% to about 8% and more preferably from about 3%to about 6%.

The composition of the invention may optionally also include one or moreconventional additives whose uses are well known to those skilled in theart. The use of such additives may be desirable in enhancing theprocessing of the compositions as well as improving the products orarticles formed therefrom. Examples of such include: oxidative andthermal stabilizers, lubricants, mold release agents, flame-retardingagents, oxidation inhibitors, dyes, pigments and other coloring agents,ultraviolet light stabilizers, organic or inorganic fillers includingparticulate and fibrous fillers, reinforcing agents, nucleators,plasticizers, as well as other conventional additives known to the art.Such may be used in amounts of up to about 10% by weight of the overallcomposition.

Representative ultraviolet light stabilizers include various substitutedresorcinols, salicylates, benzotriazole, benzophenones, and the like.Suitable lubricants and mold release agents include stearic acid,stearyl alcohol, and stearamides. Exemplary flame-retardants includeorganic halogenated compounds, including decabromodiphenyl ether and thelike as well as inorganic compounds. Suitable coloring agents includingdyes and pigments include cadmium sulfide, cadmium selenide, titaniumdioxide, phthalocyanines, ultramarine blue, nigrosine, carbon black andthe like. Representative oxidative and thermal stabilizers include thePeriod Table of

Element's Group I metal halides, such as sodium halides, potassiumhalides, lithium halides; as well as cuprous halides; and further,chlorides, bromides, iodides. Also, hindered phenols, hydroquinones,aromatic amines as well as substituted members of those above mentionedgroups and combinations thereof. Exemplary plasticizers include lactamssuch as caprolactam and lauryl lactam, sulfonamides such aso,p-toluenesulfonamide and N-ethyl, N-butyl benylnesulfonamide, andcombinations of any of the above, as well as other plasticizers known tothe art.

Suitable fillers include inorganic fillers, including those of fibrousand granular nature, as wells as mixtures thereof. The fibrous fillersinclude glass, silica glass, ceramic, asbestos, alumina, siliconcarbide, gypsum, metal (including stainless steel) as well as otherinorganic and carbon fibers. The granular fillers include wollastonite,sericite, asbestos, talc, mica, clay, kaolin, bentonite, and silicates,including alumina silicate. Other granular fillers include metal oxides,such as alumina, silica, magnesium oxide, zirconium oxide, titaniumoxide. Further granular fillers include carbonates such as calciumcarbonate, magnesium carbonate, and dolomite, sulfates including calciumsulfate and barium sulfate, boron nitride, glass beads, silicon carbide,as well as other materials not specifically denoted here. These fillersmay be hollow, for example glass microspheres, silane balloon, carbonballoon, and hollow glass fiber. Preferred inorganic fillers includeglass fibers, carbon fibers, metal fibers, potassium titanate whisker,glass beads, glass flakes, wollastonite, mica, talc, clay, titaniumoxide, aluminum oxide, calcium carbonate and barium sulfate.Particularly, glass fiber is most preferred. The inorganic fillersshould preferably be treated with silane, titanate, or anotherconventional coupling agent, and glass fibers should preferably betreated with an epoxy resin, vinyl acetate resin or other conventionalconverging agent.

Preferably the polyamide compositions are produced via a melt extrusioncompounding of the polyamide with the other composition components. Thecomposition may be formed by dry blending solid particles or pellets ofeach of the polyamide components and then melt blending the mixture in asuitable mixing means such as an extruder, a roll mixer or the like.Typical melting temperatures range from about 230° C. to about 300° C.,preferably from about 235° C. to about 280° C. and more preferably fromabout 240° C. to about 260° C. for nylon 6 and its copolymers. Blendingis conducted for a period of time required to attain a substantiallyuniform blend. Such may easily be determined by those skilled in theart. If desired, the composition may be cooled and cut into pellets forfurther processing, it may be extruded into a fiber, a filament, or ashaped element or it may be formed into films and optionally uniaxiallyor biaxially sketched by means well known in the art.

The barrier polyamide films and articles of this invention may beproduced by any of the conventional methods of producing films andarticles, including extrusion and blown film techniques, bottles viaextrusion or injection stretch blow molding and containers viathermoforming techniques. Processing techniques for making films,sheets, containers and bottles are well known in the art. For example,the polyamides may be preblended and then the blend fed into an infeedhopper of an extruder, or each polyamide may be fed into infeed hoppersof an extruder and then blended in the extruder. The melted andplasticated stream from the extruder is fed into a single manifold dieand extruded into a layer. It then emerges from the die as a singlelayer film of nylon material. After exiting the die, the film is castonto a first controlled temperature casting roll, passes around thefirst roll, and then onto a second controlled temperature roll, which isnormally cooler than the first roll. The controlled temperature rollslargely control the rate of cooling of the film after it exits the die.Once cooled and hardened, the result film is preferably substantiallytransparent.

Alternatively the composition may be formed into a film using aconventional blown film apparatus. The film forming apparatus may be onewhich is referred to in the art as a “blown film” apparatus and includesa circular die head for bubble blown film through which the plasticizedfilm composition is forced and formed into a film “bubble”. The “bubble”is ultimately collapsed and formed into a film.

The composition may also be used to form shaped article through any wellknown process, including extrusion blow molding and injectionstretch-blow molding. An injection molding process softens thethermoplastic nylon blend in a heated cylinder, injecting it whilemolten under high pressure into a closed mold, cooling the mold toinduce solidification, and ejecting the molded preform from the mold.Molding compositions are well suited for the production of preforms andsubsequent reheat stretch-blow molding of these preforms into the finalbottle shapes having the desired properties. The injection moldedpreform is heated to suitable orientation temperature in the 100°C.-150° C. range and then stretch-blow molded. The latter processconsists of first stretching the hot preform in the axial direction bymechanical means such as by pushing with a core rod insert followed byblowing high pressure air (up to 500 psi) to stretch in the hoopdirection. In this manner, a biaxially oriented blown bottle is made.Typical blow-up ratios range from 5/1 to 15/1.

The barrier polyamide composition of this invention may be formed as anintegral layer in a multilayered film, bottle or container which includeone or more layers of another thermoplastic polymer such aspolyesters-particularly polyethylene terephthalate (PET) and PETcopolymers, polyolefins, ethylene vinyl alcohol copolymers,acrylonitrilecopolymers, acrylic polymers, vinyl polymers,polycarbonate, polystyrene, etc. The polyamide composition of thisinvention is particularly suitable as a barrier layer in theconstruction and fabrication of multilayer bottles and thermoformedcontainers in which PET or polyolefin function as structural layers.Such PET/polyamide multilayer bottles can be made by coinjectionstretch-blowmolding process similar to the injection-stretch blowmoldingprocess describe before. Similarly, polyamide/polyolefin multilayerbottles can be made by coextrusion blowmolding. The latter processusually employs suitable tie layers for adhesion.

Useful polyesters for coinjection stretch blowmolding process includepolyethylene terephthalate (PET) and its copolymer in the intrinsicviscosity (I.V.) range of 0.5-1.2 dl/g range, more preferably in theI.V. range of 0.6 to 1.0 and most preferably in the I.V. range of0.7-0.9. The polyolefins used in the coextrusion blowmolding includepolymers of alpha-olefin monomers having from about 2 to about 6 carbonatoms and includes homopolymers, copolymers (including graftcopolymers), and terpolymers of alpha-olefins. Illustrative homopolymerexamples include ultra low density (ULDPE), low density (LDPE), linearlow density (LLDPE), medium density (MDPE), or high density polyethylene(HDPE); polypropylene; polybutylene; polybutene-1;poly-3-methylbutene-1; poly-pentene-1; poly-4-methylpentene-1;polyisobutylene; and polyhexene. The polyolefin may have a weightaverage molecular weight of about 1,000 to about 1,000,000, andpreferably about 10,000 to about 500,000. Preferred polyolefins arepolyethylene, polypropylene, polybutylene and copolymers, and blendsthereof. The most preferred polyolefins are polyethylene andpolypropylene.

Copolymers of ethylene and vinyl alcohol suitable for use in the presentinvention can be prepared by the methods disclosed in U.S. Pat. Nos.3,510,464; 3,560,461; 3,847,845; and 3,585,177. Additional layers mayalso include adhesive tie layers to tie various layers together.Non-limiting examples of other optional polymeric layers and adhesive ortie layers which can be used in the film laminate of the presentinvention are disclosed in U.S. Pat. Nos. 5,055,355; 3,510,464;3,560,461; 3,847,845; 5,032,656; 3,585,177; 3,595,740; 4,284,674;4,058,647; and 4,254,169.

The multilayered barrier articles of this invention can be formed by anyconventional technique for forming films, including lamination,extrusion lamination, coinjection, stretch-blow molding and coextrusionblowmolding. The preferred method for making multilayer film is bycoextrusion. For example, the material for the individual layers, aswell as any optional layers, are fed into infeed hoppers of theextruders of like number, each extruder handling the material for one ormore of the layers. The melted and plasticated streams from theindividual extruders are fed into a single manifold co-extrusion die.While in the die, the layers are juxtaposed and combined, then emergefrom the die as a single multiple layer film of polymeric material.After exiting the die, the film is cast onto a first controlledtemperature casting roll, passes around the first roll, and then onto asecond controlled temperature roll, which is normally cooler than thefirst roll. The controlled temperature rolls largely control the rate ofcooling of the film after it exits the die. In another method, the filmforming apparatus may be one which is referred to in the art as a blownfilm apparatus and includes a multi-manifold circular die head forbubble blown film through which the plasticized film composition isforced and formed into a film bubble which may ultimately be collapsedand formed into a film. Processes of coextrusion to form film and sheetlaminates are generally known. See for example in “Modern PlasticsEncyclopedia”, Vol. 56, No. 10A, pp. 131-132, McGraw Hill, October 1979.Alternatively the individual layers may first be formed into sheets andthen laminated together under heat and pressure with or withoutintermediate adhesive layers.

Adjacent to the fluoropolymer layer is an adhesive layer, also referredto in the art as a “tie” layer, between each film layer. In accordancewith the present invention, suitable adhesive polymers include modifiedpolyolefin compositions having at least one functional moiety selectedfrom the group consisting of unsaturated polycarboxylic acids andanhydrides thereof. Such unsaturated carboxylic acid and anhydridesinclude maleic acid and anhydride, fumaric acid and anhydride, crotonicacid and anhydride, citraconic acid and anhydride, itaconic acid ananhydride and the like. Of these, the most preferred is maleicanhydride. The modified polyolefins suitable for use in this inventioninclude compositions described in U.S. Pat. Nos. 3,481,910; 3,480,580;4,612,155 and 4,751,270 which are incorporated herein by reference.Other adhesive layers non-exclusively include alkyl ester copolymers ofolefins and alkyl esters of α,β-ethylenically unsaturated carboxylicacids such as those described in U.S. Pat. No. 5,139,878. The preferredmodified polyolefin composition comprises from about 0.001 and about 10weight percent of the functional moiety, based on the total weight ofthe modified polyolefin. More preferably the functional moiety comprisesfrom about 0.005 and about 5 weight percent, and most preferably fromabout 0.01 and about 2 weight percent. The modified polyolefincomposition may also contain up to about 40 weight percent ofthermoplastic elastomers and alkyl esters as described in U.S. Pat. No.5,139,878.

Nylon films produced according to the present invention may be orientedby stretching or drawing the films at draw ratios of from about 1.1:1 toabout 10:1, and preferably at a draw ratio of from about 2:1 to about5:1. The term “draw ratio” as used herein indicates the increase ofdimension in the direction of the draw. Therefore, a film having a drawratio of 2:1 has its length doubled during the drawing process.Generally, the film is drawn by passing it over a series of preheatingand heating rolls. The heated film moves through a set of nip rollsdownstream at a faster rate than the film entering the nip rolls at anupstream location. The change of rate is compensated for by stretchingin the film.

The film may be stretched or oriented in any desired direction usingmethods well known to those skilled in the art. The film may bestretched uniaxially in either the longitudinal direction coincidentwith the direction of movement of the film being withdrawn from the filmforming apparatus, also referred to in the art as the “machinedirection”, or in as direction which is perpendicular to the machinedirection, and referred to in the art as the “transverse direction”, orbiaxially in both the longitudinal direction and the transversedirection.

The thickness of the polyamide film is preferably from about 0.05 mils(1.3 μm) to about 100 mils (2540 μm), and more preferably from about0.05 mils (1.3 μm) to about 50 mils (1270 μm). While such thicknessesare preferred as providing a readily flexible film, it is to beunderstood that other film thicknesses may be produced to satisfy aparticular need and yet fall within the scope of the present invention;such thicknesses which are contemplated include plates, thick films, andsheets which are not readily flexible at room temperature (approx. 20°C.).

One noteworthy characteristic of the articles made from the compositionsof this invention is that they exhibit excellent gas barrier properties,particularly oxygen barrier properties. Oxygen permeation resistance orbarrier may be measured using the procedure of ASTM D-3985. In general,the films of this invention have an oxygen transmission rate (O₂ TR) at90% relative humidity less than about 1.0 cm³/100 in²(645 cm²)/24hrs/Atm at 23° C. and usually less than about 0.5 cm³/100 in²(645cm²)/24 hrs/Atm at 23° C.

The following non-limiting examples serve to illustrate the invention.

Processing Details

Reactive Extrusion

Process 1: A Leistritz 18-mm co-rotating twin screw extruder equippedwith a K-Tron volumetric feeder was employed. The polybutadiene (eithercarboxy terminated polybutadiene—Hycar, or epoxy functionalizedpolybutadiene—Elf-Atochem Poly BD 600/Poly BD605E) was stored in asealed drum and metered with a Nichols-Zenith pump directly into asealed extruder barrel directly following the feed barrel. Thepolybutadiene was injected prior to the first (of two) mixing zones viaa Leistritz direct liquid injection nozzle. Nylon 6 pellets, or blendsof nylon 6/amorphous nylon, nylon 6/EVOH, or other materials, were fedinto the nitrogen-blanketed throat of the extruder at a rate of 10pounds (22 kg) per hour. The polybutadiene was pumped at a rate suchthat weight percentages of 1% to 5% polybutadiene were added. Theextruder was equipped with two mixing zones consisting primarily ofkneading elements. The extruder was equipped with a vacuum zonesubsequent to the second mixing zone and prior to the die plate. Theextrudate was quenched in a water bath and then pelletized.

Process 2: A Leistritz 18-mm co-rotating twin screw extruder equippedwith a K-Tron volumetric feeder was employed. The polybutadiene (eithercarboxy terminated polybutadiene—Hycar, or epoxy functionalizedpolybutadiene—Elf-Atochem Poly BD 600/Poly BD 605E) was stored in asealed drum and metered with a Nichols-Zenith into the extruder throat.Nylon 6 pellets or other materials were fed into the nitrogen-blanketedthroat of the extruder at a rate of 5 pounds (11 kg) per hour. Thepolybutadiene was pumped at a rate such that weight percentages of 1% to5% polybutadiene were added. The extruder was equipped with two mixingzones consisting primarily of kneading elements. The extrudate wasquenched in a water bath and then pelletized.

Process 3: A Leistritz 18-mm co-rotating twin screw extruder equippedwith a K-Tron volumetric feeder was employed. A blend of nylon 6 pelletsand cobalt stearate pastilles were fed into the nitrogen-blanketedthroat of the extruder at a rate of 10 pounds (22 kg) per hour. Theblend consisted of 95% nylon 6 and 5% cobalt stearate. The extruder wasequipped with two mixing zones consisting primarily of kneadingelements. The extrudate was quenched in a water bath and thenpelletized. The resulting pellet was used as a masterbatch additive insome of the processes listed below.

Process 4: A Leistritz 18-mm co-rotating twin screw extruder equippedwith a K-Tron volumetric feeder was employed. The polybutadiene (eithercarboxy terminated polybutadiene—Hycar, or epoxy functionalizedpolybutadiene—Elf-Atochem Poly BD 600/Poly BD 605E) was stored in asealed drum vessel and metered with a Nichols-Zenith pump directly inthe extruder barrel following the feed throat. The polybutadiene wasinjected directly into the extruder prior to the first (of two) mixingzones via a Leistritz direct liquid injection nozzle. A blend of nylon 6and cobalt stearate masterbatch was fed into the nitrogen-blanketedthroat of the extruder at a rate of 10 pounds per hour. The blendconsisted of approximately 98 weight percent nylon 6 and 2 weightpercent cobalt masterbatch. The polybutadiene was pumped at a rate suchthat weight percentages of 1% to 5% polybutadiene were added. Theextruder was equipped with two mixing zones consisting primarily ofkneading elements. The extruder was equipped with a vacuum zonesubsequent to the second mixing zone and prior to the die plate. Theextrudate was quenched in a water bath and then pelletized.

Pellet Blending

Process 5: Blending of 98 weight percent material prepared in process 1or 2 (or other material) and 2 weight percent material prepared inprocess 3 . Blending was accomplished by weighing out required amount ofeach material into a large container. The container was tumbled forapproximately 5 minutes to ensure thorough mixing of the two components.These blends were used subsequently as feedstock for cast filmprocessing.

Cast Film

Process 6: A Haake single screw extruder equipped with a six-inch (152.4mm) wide film die was flood fed with pellets from process 3, 5 or 6.Extruder temperature was set at approximately 260° C. Extrudate passedthrough the slit die onto a heated Killion cast roll. Film thickness wasadjusted via cast roll speed and/or screw RPM to prepare a film withtypical thickness of 0.001 inch to 0.003 inch (0.0254 to 0.0762 mm).

Process 7: A Killion 1.5 inch (38.1 mm) single screw extruder equippedwith a twelve-inch wide film die was flood fed with pellets from process3, 5 or 6. Extruder temperature was set at approximately 260° C.Extrudate passed through the slit die onto a heated Killion cast roll.Film thickness was adjusted via cast roll speed and/or screw RPM toprepare a film with typical thickness of 0.001 inch to 0.003 inch(0.0254 to 0.0762 mm).

Process 8: Three Killion single screw extruders equipped with atwelve-inch wide film coextrusion die were utilized to prepare athree-layer film. One extruder was flood fed with pellets from process5. Two extruders were flood fed with approximately 1.0IV PET. Extrudertemperatures were approximately 260° C. for pellets from process 5 and280° C. for PET pellets. Extrudate passed through the slit die onto aheated cast roll. Film thickness was adjusted via cast roll speed and/orscrew RPM to prepare a film of the following thickness: 0.004 inch(0.1016 mm) PET outer layers and 0.002 inch (0.0508 mm) active barriernylon inner layer.

Oxygen Transmission Measurements

Oxygen transmission measurements were conducted on film samples on aMocon Oxtran 2/20 apparatus equipped with SL sensors. Tests wereconducted at 80% to 90% relative humidity in air (21% oxygen). Data werecollected as a function of time and recorded in units of: cc-mil/100in²/atm day. Tests were conducted for up to 28 days.

Description of Examples

Listed in the Table are the summarized results obtained from thefollowing examples which illustrate the effect on oxygen transmissionrate of the oxygen binding system described herein.

Comparative Examples 1-8

Comparative examples 1-8 are useful as reference points or “baselines”for the examples which will be described later. Comparative example 1 isa commercial grade nylon 6 homopolymer available from Honeywell.Comparative example 2 is a nylon 6 homopolymer containing 100 ppmcobalt. Comparative example 2 illustrates that a 100 ppm addition ofcobalt to nylon 6 has no affect on the oxygen transmission rate of nylon6. Comparative example 3 is a nylon 6 homopolymer containing 3 weightpercent Poly BD 600. This example illustrates that the addition of 3weight percent Poly BD 600 (epoxy functionalized 1,3 polybutadiene) tonylon 6 worsens the oxygen transmission rate. Comparative example 4 isan experimental grade nylon 6/nanoclay blend (Nanomer I24TL organoclaypolymerized in situ with nylon 6). Comparative example 5 is acommercially available nylon 6/nanocomposite from Unitika. Comparativeexample 6 is a commercially available semi-aromatic nylon 6 fromMitsubishi (MXD6). Comparative example 7 is MXD6 containing 100 ppmcobalt. Comparative example 8 is a commercially available amorphousnylon (Grivory) available from EMS.

EXAMPLES 1-9

Examples 1-9 illustrate the effect of the oxygen binding system on theoxygen transmission rate of nylon 6. The examples illustrate thedramatic improvement in oxygen binding ability of the copolymers of thisinvention. In general for all examples the oxygen binding epoxyfunctionalized polybutadiene is nano/micro-phase separated from thenylon matrix with; polybutadiene particle size on the order of 10-1000nm. Example 1 is a copolymer of this invention containing 1 weightpercent Poly BD 600 and 100 ppm by weight of cobalt. Samples of thisexample were prepared by methods 1, 3, 5 and 6 (described above).Example 2 is the same as example 1 except it contains 2 weight percentPoly BD 600. Example 3 is the same as example 1 except it contains 3weight percent Poly BD 600. The oxygen transmission rate of example 3decreases rapidly to near zero (3.4 E-3 cc mil/100 in²/atm day after 2days) and remains low (less than 0.1 cc mil/100 in²/atm day) for fivedays. Example 4 is similar to example one except that compounding method2 was used rather than compounding method 1 (each described above).Compounding method 1 is preferable because whiter pellets are obtained.Whiter pellets are the result of direct liquid injection of Poly BD600/605E into the extruder in the absence of air which preventsoxidation of the polybutadiene). The oxygen transmission rate of example4 results in very low oxygen transmission rate for 5 days. Examples 3and 4 have an average 65 times lower oxygen transmission rate of over a5 day period relative to comparative examples 1, 2 and 3. Example 5 is acopolymer of this invention containing three weight percent Poly BD 600and 100 ppm by weight cobalt. This example, in which the cobalt and PolyBD 600 were added simultaneously to the same extruder (methods 4 and 7described above), exhibited a low oxygen transmission rate for 3 days.Examples 3 and 5 were comparable in their oxygen scavenging behavior andwere an average 25 times lower in oxygen transmission rate over a 5 dayperiod relative to comparative examples 1, 2 and 3. This illustratesthat the oxygen binding effect is observed in films prepared from twodifferently prepared starting materials, i.e. (1) a pellet blendapproach (methods 1, 2 and 3) or (2) a filly compounded approach (method4). Example 6 is the same as Example 3 except that Poly BD 605E (higherepoxy functionality relative to Poly BD 600) was used. Example 7 issimilar to example eight except it contains 4 weight percent Poly BD600. Example 8 is a copolymer of this invention containing 5 weightpercent Hycar carboxy terminated polybutadiene (Hycar CTB). Samples wereprepared by methods 2, 3, 5 and 7. The oxygen transmission ratesmeasured on this example illustrate that Hycar CTB is a less effectiveoxygen binding polybutadiene. However, this example did exhibit loweroxygen transmission rates than comparative examples 1, 2 and 3. Example9 is a co-extruded cast film example comprised of example three as abarrier layer between two PET outer layers. The sample was made withprocess steps 1, 3, 5 and 8. The outer layers of PET result in a filmwith a longer near zero oxygen transmission rate as compared with a neatfilm of the barrier layer (example 3). The oxygen transmission data forcomparative example 1 and examples 6 and 9 are given in FIG. 1.

EXAMPLES 10-13

Examples 10-13 illustrate the effect of the oxygen binding system on theoxygen transmission rate of a nylon 6/organo-clay blend of thisinvention and a commercially available grade of nylon 6/organo-clayblend. The oxygen transmission data for examples 11 and 13 andcomparative examples 1, 4 and 5 are given in FIG. 2. These examplesillustrate the dramatic improvement in oxygen binding ability of thecopolymers of this invention. Further, these examples demonstrate thesynergistic effect of combining the oxygen binding system of thisinvention with a nylon 6 with organo-clay). The passive barrier affordedby the organo-clay combined with the active barrier of the oxygenbinding copolymers result in a nylon 6 material with dramaticallyimproved oxygen transmission properties. Example 10 is a copolymer ofthis invention containing 98 weight percent nylon 6/nanocomposite(containing 6 weight percent Nanocor Nanomer I24T), 2 weight percentPoly BD 600 and 100 ppm by weight cobalt and was prepared by methods 1,3, 5 and 6. The oxygen transmission rate of example 10 is near zero for10 days (test duration) and is 225 times less than comparative examples1, 2 and 3. Example 11 is the same as example 10 except it contains 3weight percent Poly BD 600. This example has a near zero oxygentransmission rate for 10 days (test duration) and is more than 900 timeslower in oxygen transmission rate relative to comparative examples 1, 2and 3. Example 12 was prepared as a blend of 77 weight percent nylon6/organo-clay blend (containing 6 weight percent Nanocor Nanomer I24T),20 weight percent amorphous nylon (EMS Grivory G21), 3 weight percentPoly BD 600 and 100 ppm cobalt. This example exhibited a very low oxygentransmission rate for 16 days (test duration) and is at least 105 timeslower in oxygen transmission rate relative to comparative examples 1, 2and 3. Example 13 is a copolymer of this invention containing 95% nylon6/organo-clay blend (commercially available from Unitika), 5 weightpercent Poly BD 600 and 100 ppm cobalt. This example exhibited a verylow oxygen transmission rate for 26 days (test duration) and is 300times lower in oxygen transmission rate relative to comparative examples1, 2 and 3. There exists a strong synergy when a passive barrier(organo-clay) is combined with an active barrier system (epoxyfunctionalized polybutadiene/cobalt). This may be the result ofincreased “tortuosity” for oxygen diffusing through the barrier materialdue to the elongated (high aspect ratio) clay particles and the presenceof the highly dispersed and finely sized polybutadiene phase. Oxygenmolecules are blocked by the clay particles and then forced to the epoxyfunctionalized polybutadiene phase where they become chemically bound.

EXAMPLE 14

Example 14 relate to poly(m-xylyleneadipamide), a polymer prepared fromequimolar amounts of the two monomers (1) metaxylylene diamine and (2)adipic acid. This polymer is usually referred to as MXD-6. Example 14was prepared by melt compounding 6 weight percent clay (Rheox) andMXD-6. Subsequent to this compounding step 3 weight percent Poly BD 600and 100 ppm cobalt were added by methods 2, 3, 5 and 6. This sampleexhibited a low oxygen transmission rate, and improved by a factor of 2(in oxygen transmission rate) relative to comparative example 7, and bya factor of 4 relative to comparative example 6.

EXAMPLES 15-17

Examples 15-17 illustrate the effect of the oxygen binding system onamorphous nylon and blends of nylon and amorphous nylon. Example 15 is acopolymer of this invention containing 97 weight percent amorphous nylon(EMS Grivory G21), 3 weight percent Poly BD600 and 100 ppm cobalt.Example 16 was prepared as 68 weight percent nylon 6 homopolymer blendedwith 29 weight percent amorphous nylon, 3 weight percent Poly BD 600 and100 ppm cobalt (prepared by processes 1, 3, 5 and 6). Example 17 wasprepared as 22 weight percent nylon 6, 67 weight percent amorphousnylon, 8 weight percent Nanomer I24TL organoclay, 3 percent Poly BD 600and 100 ppm cobalt (prepared by processes 1, 3, 5 and 6). Each of theseexamples exhibited oxygen scavenging and resulted in lower oxygentransmission rates relative to comparative example 8.

EXAMPLES 18-21

Examples 18-21 illustrate the effect of the oxygen binding system onEVOH and blends of nylon and EVOH. Example 18 is a blend containing 70weight percent nylon 6, and 30 weight percent EVOH. Example 19 wasprepared as 70 percent nylon 6/organo-clay blend (containing 6 weightpercent Nanocor Nanomer I24T) and 30 weight percent EVOH. Example 20 wasprepared as 69 weight percent nylon 6, 28 weight percent EVOH and 3weight percent Poly BD 600/ Example 21 was prepared as 69 weight percentnylon 6/organo-clay blend (containing 6 weight percent Nanocor NanomerI24T), 28 weight percent EVOH and 3 weight percent Poly BD 600. Examples18-21 were prepared by process steps 1, 3, 5 and 6. The samplescontaining the oxygen scavenging copolymer exhibit oxygen scavenging andresulted in low oxygen transmission rates.

Wt. % Wt. % PPM OTR^(‡) OTR OTR OTR OTR OTR OTR OTR OTR Example No.Process Steps PBD* Nylon 6 Co Day 1 Day 2 Day 3 Day 4 Day 5 Day 7 Day 10Day 16 Day 26 Comparative 1 6 0 100  0 1.7 1.6 1.6 1.6 1.6 N/A N/A N/AN/A Comparative 2 3, 5, 6 0 100 100 1.7 1.6 1.6 1.6 1.6 N/A N/A N/A N/AComparative 3 2, 6 3  97  0 1.9 1.9 1.9 1.9 1.9 1.9 N/A N/A N/AComparative 4 6 0 100^(a)  0 0.27 0.29 0.3 0.3 0.3 N/A N/A N/A N/AComparative 5 7 0  100^(b)  0 N/A N/A N/A N/A N/A 0.24 N/A N/A N/AComparative 6 6 0 100^(c)  0 0.18 0.16 0.17 0.17 N/A N/A N/A N/A N/AComparative 7 3, 5, 6 0 100^(c) 100 0.067 0.079 0.090 0.082 N/A N/A N/AN/A N/A Comparative 8 6 0  100^(d)  0 0.3 0.3 0.3 0.3 N/A N/A N/A N/AN/A    1 1, 3, 5, 6 1  99 100 0.07 0.02 0.25 0.42 N/A N/A N/A N/A N/A   2 1, 3, 5, 6 2  98 100 0.02 0.07 0.16 0.28 0.4 0.62 N/A N/A    3 1,3, 5, 6 3  97 100 0 0.0034 0.0086 0.026 0.097 0.54 N/A N/A N/A    4 2,3, 5, 7 3  97 100 0.0075 0.0069 0.0097 0.034 0.11 0.53 N/A N/A N/A    54, 7 3  97 100 0 0.0091 0.046 0.15 0.38 N/A N/A N/A N/A    6 1, 3, 5, 6 3^(†)  97 100 1.2 0.65 0.027 0.016 0.012 0.018 0.14  N/A N/A    7 1, 3,5, 6 4  96 100 0.0098 0 0.02 0.08 0.17 0.48 0.75  N/A N/A    8 2, 3, 5,7   5^(††)  95 100 0.14 0.68 0.98 1.1 1.3 1.4 N/A N/A N/A    9 1, 3, 5,8 3  97 100 0.008 0.008 0.008 0.008 0.009 0.01 0.028 N/A N/A   10 1, 3,5, 6 2   98^(a) 100 0.05 0.0063 0.0063 0.0076 0.007 0.008 N/A N/A   111, 3, 5, 6 3   97^(a) 100 0 0 0.00006 0.00026 0.0008 0.002 0.002 N/A N/A  12 1, 3, 5, 6 3 77^(a), 20^(d) 100 0.27 0.11 0.0084 N/A 0.010 0.0140.027 0.042 N/A   13 2, 3, 5, 7 5   95^(b) 100 0.044 0.006 0.006   142^(f), 3, 5, 6 3   97^(c) 100 0.014 0.028 0.037 0.040 0.046 0.044 N/AN/A N/A *Elf Atochem Poly BD 600 (unless otherwise noted) ^(†)ElfAtochem PolyBD605E ^(††)Goodrich Hycar CTB ^(‡)Units: cc mil/100 in²/atmday, RH = 80-90% unless otherwise noted, Tested in air (21% O₂). Toconvert to cc mm/m²/atm day, multiply by 3.94 × 10⁻¹. ^(a)Polymerizednylon6/nanoclay (Nanocor I24TL organoclay) ^(b)Commercially availablenylon 6 nanocomposite from Unitika ^(c)Commercially available nylon 6from MGC (MXD-6) ^(d)Commercially available amorphous nylon from EMS(Grivory G21) ^(e)Commercially available EVOH from EVAL Co. ^(f)6% Rheox2355 clay pre-blended in MXD6 prior to process step number 2. ^(g)8%Nanomer I24TL organoclay added to twin screw extruder during process 1.

The foregoing examples illustrate the effect of the oxygen bindingsystem on the oxygen transmission rate of the inventive nyloncomposition. While the present invention has been particularly shown anddescribed with reference to preferred embodiments, it will be readilyappreciated by those of ordinary skill in the art that various changesand modifications may be made without departing from the spirit andscope of the invention. It is intended that the claims be to interpretedto cover the disclosed embodiment, those alternatives which have beendiscussed above and all equivalents thereto.

What is claimed is:
 1. A polyamide composition which comprises apolyamide homopolymer, copolymer, or blends thereof, at least onepolyamide reactive, oxidizable polydiene or oxidizable polyether, and anoxidation promoting metal salt catalyst.
 2. The composition of claim 1which comprises a polyamide reactive, oxidizable polyether.
 3. Thecomposition of claim 1 which comprises a polyamide reactive, oxidizablepolydiene.
 4. The composition of claim 1 wherein the polyamide reactive,oxidizable polydiene comprises a polybutadiene.
 5. The composition ofclaim 1 wherein the polyamide reactive, oxidizable polydiene comprisesan epoxy or anhydride functional polybutadiene.
 6. The composition ofclaim 1 wherein the polyamide reactive, oxidizable polyether comprisesan epoxy or anhydride functional polyether.
 7. The composition of claim1 wherein the polyamide reactive, oxidizable polydiene or oxidizablepolyether is in the form of particles which are substantially uniformlydistributed in the polyamide homopolymer, copolymer, or blend thereof.8. The composition of claim 1 wherein the oxidizable polydiene oroxidizable polyether is in the form of particles whose average particlesize is in the range of from about 10 nm to about 100 nm, and whichparticles are substantially uniformly distributed in the polyamidehomopolymer, copolymer, or blend thereof.
 9. The composition of claim 1wherein the metal salt catalysts comprises a metal carboxylate saltcatalyst.
 10. The composition of claim 1 wherein the metal salt catalystcomprises a metal carboxylate salt catalyst selected from the groupconsisting of metal acetates, stearates, propionates, hexanoates,octanoates, benzoates, salicylates and cinnamates.
 11. The compositionof claim 1 wherein the metal salt catalyst comprises a metal carboxylatesalt catalyst selected from the group consisting of a cobalt, copper orruthenium, acetate, stearate, propionate, hexanoate, octanoate,benzoate, salicylate or cinnamate, or combinations thereof.
 12. Thecomposition of claim 1 wherein the polyamide homopolymer or copolymer orblends thereof are aliphatic or aliphatic/aromatic.
 13. The compositionof claim 1 wherein said polyamide comprises nylon
 6. 14. The compositionof claim 1 wherein said polyamide comprises nylon 6,6.
 15. Thecomposition of claim 1 wherein said polyamide comprises nylon MXD6. 16.The polyamide composition of claim 1 in the form of a blend of saidpolyamide homopolymer, copolymer, or blends thereof, and said at leastone polyamide reactive, oxidizable polydiene or oxidizable polyether.17. The polyamide composition of claim 1 in the form of a reactionproduct of said polyamide homopolymer, copolymer, or blends thereof, andsaid at least one polyamide reactive, oxidizable polydiene or oxidizablepolyether.
 18. A process for producing a polyamide composition whichcomprises melting a polyamide homopolymer, copolymer, or blends thereof,and blending the molten polyamide homopolymer, copolymer, or blendthereof with at least one polyamide reactive, oxidizable polydiene oroxidizable polyether and an oxidation promoting metal salt catalyst toform a mixture, and then cooling the mixture.